Selecting correct tolerance for machined components

Concerning the tolerance of machined components. 

Generally, the dimensional tolerance is determined first.

And then the shape and position tolerance is determined. When we design the machined components, for the reasonable tolerance, we should consider the function needs first, the second is the processing technology.

The last is the assembly and maintenance technology.

For example, assembly hole and shaft, it is not only a round hole and shaft, can be square,but we usually use round, because the convenient processing. Traditional processing methods such as turning, milling, drilling and grinding,most of the circular processing. Now with the popularity of laser cutting and wire cutting,the application of special-shaped hole is also more.At the same tolerance level,the processing cost of square hole is higher than round hole.

Since the traditional method of processing is circular processing, the choice of hole and shaft will have a basic hole system and basic shaft system.

Generally, we can get hole by drilling, reaming, and milling. For convenient machining, we should choose to have readily available tools (drill, reamer,cutter) size, such as the diameter 14mm of cutting tool are very rare, we can choose 12mm,15mm or 16mm diameter of cutting tools,which is a conveninet purchase specifications. In this way, the manufacturing cost is very low. For example,choose diameter 30mm not 27mm, although your computing needs 27mm.

The fit of hole and shaft includes clearance fit, transition fit and interference fit.

Learn more about tolerance of machined components.

7 kinds of clamping method of turning eccentric parts

In mechanical transmission, the rotary motion into reciprocating linear motion or linear motion into rotary motion, usually with an eccentric shaft or crankshaft to complete.Eccentric shaft that is parallel to the axis of the parts between the cylindrical outer and without overlap. The method of turning eccentric parts,according to different quantity,shape and precision of the machined parts.

Turning + Grinding Parts

There are 7 kinds of clamping method of turning eccentric parts.

1. With four-jaw chuck turning 

This method is suitable for processing eccentricity smaller, less precision, shorter and smaller quantity of eccentric parts.

2.With three-jaw self centering chuck turning

This method is suitable for mass production,shorter and smaller eccentricity,less precise eccentric parts. Spacer should be added in a claw of three-jaw self-centering chuck.

3.With double chuck turning

This method is suitable for processing short length,eccentricity is small,a large quantity of eccentric parts. Should adjust the eccentricity before processing.

4. With faceplate turning 

This method is suitable for the shorter length,the larger eccentricity,less precise eccentric parts.Before machining eccentric hole,the firs processing is turning out diameter and two ends surface,and then machining the eccentric hole.

5.With eccentric chuck turning

This method is suitable for processing short axis,the disc,tube with high precision eccentric parts.

6.With two top turning eccentric parts

This method is suitable for processing longer eccentric parts,before machining the parts,should draw the center point and eccentric point on both sides of the parts,and then turning.

7. With special fixture turning eccentric parts

This method is suitable for high-precision machining, and larger quantities of eccentric parts. Before processing should be processed from the corresponding eccentric shaft or eccentric according to the eccentricity of the part, and then clamping the part on eccentric shaft for turning.

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What is grinding process?

Precision Grinding Machining Parts

Grinding process is also known as grinding machining.

Grinding is machining the surface of metal parts by grinding wheel,oil stone and abrasive.The machine tool that uses grinding wheel is usually called grinding machine,the machine tool that uses oil stone and abrasive is called precise grinding machine.

The grinding wheel is a cutting tool with a lot of small and extremely hard abrasive particles.From its cutting action,each of the fine grinding granules on the surface of grinding wheel, the effect is equal to a subtle blade.grinding machining just like countless subtle blade cut at the same time.

In grinding process,blunt the edges of the grinding grain,since the effect of cutting force,It often breaks or falls off to reveal a new sharp sharpen,This kind of
The phenomenon is called self -sharpness of grinding wheel.

The abrasive grinding process produces a lot of heat,So we need to cool down with a lot of flowing cooling water.

The range of grinding is very wide,almost any surface can be machined with grinding,such as inner and outer cylinder,Internal and external cone,kinds of plane,the screw thread,gear, spline, forming surface.Further more,it is hard to process hard materials such as hardened steel and hard alloy.

SYM Grinding Team

Due to the multiple blade and self-sharpness of  grinding wheel, high cutting speed and The grinding machine has high precision,the precision and surface finish of metal parts are high after grinding,The average grinding precision reaches grade 1-2, the roughness can meet Ra0.4-Ra0.8, for precise grinding parts,the surface roughness can meet Ra0.05.

At present, the grinding process is generally used as the finishing process of parts surface.However, it can also be used for rough processing of preprocessing and cleaning works.